feat: forward accept/drop metrics

[WDaan]

What would you like to be added:

I'd be nice if instead of just logging events like this, they also would tracked as a metric like cilium does.

Why is this needed:
This would allow for easy debugging/monitoring. Currently you could still do it by building dashboards on top of the log messages, but doing this through metrics would be a more ergonomic approach.

[shukla2009]

Its quite important feature specially in case of debugging

[shaunofneuron]

I'm in the process of moving away from kube-iptables-tailer and currently have no alternative for getting kubernetes events when traffic is being blocked by a network policy. It would be great to have metrics, it would be even better to have k8s events with context like pod/service (not just dest ip/src ip from event logs).